Environment Editor, The Sydney Morning Herald

Sheep eat feed given to them so they survive the drought affecting NSW. Photo: Peter Stoop

Farmers and firefighters, already dogged by a hot, dry summer for much of Australia, may face worsening conditions later in the year as prospects grow for an El Nino weather pattern in the Pacific.

A series of heatwaves and a spreading drought is expected to cut the output of summer crops by 25 per cent for 2013-14 to the lowest level since 2009-10, the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) said on Tuesday.

Victorian fire authorities, meanwhile, continued to battle at least two dozen uncontained fires on Tuesday, with 21 homes destroyed and some 330,000 hectares burnt out. The Rural Fire Service in NSW, which has sent 240 firefighters to Victoria for the rest of the month, is also working to suppress 37 fires across the state, four of them uncontained, a spokesman said.

Last six months: rain in Australia falls mainly in the west. Photo: BoM

The outlook for longer-term relief, however, is dimming, with meteorological agencies and researchers raising the odds that an El Nino will form this year.

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The weather pattern, which typically sees rainfall shift eastward away from Australia, is regularly linked to dry years with active fire seasons for southern and eastern parts of Australia.

The Bureau of Meteorology said in its fortnightly update on Tuesday that neutral conditions for the El Nino-Southern Oscillation are likely to persist at least until the end of autumn. However, warming of the Pacific is expected in coming months, with "some, but not all, models" indicating temperatures in the central Pacific "may approach El Nino levels by early winter".

Areas to receive NSW government drought help. Photo: NSW government

Researchers in Germany, however, say there is at least a three-in-four chance that an El Nino event will occur this year, according to a study published in the US Proceedings of the National Academy of Sciences on Monday.

Kevin Tolhurst, a fire ecologist at the University of Melbourne, said an El Nino would probably raise fire risks for next summer.

''We're heading back into a dry period again," Professor Tolhurst said, noting that fires were not only spreading further than in recent years but proving harder to put out.

"In El Nino years, you have much larger and more destructive fires because there's much more of the landscape available to burn," he said. Ferny gullies that often slow or stop a fire in normal years have much less moisture.

As a result, fire authorities will need to devote more resources to suppressing fires. That effort doesn't rely on "our big helicopters and the massive numbers of fire trucks - which are all really important in the emergency situation", he said. "This is the hard slog, days after the main fire run has finished, before the next series of bad weather."

Peter Collins, manager of ABARES's agricultural commodities unit, said that while it is too early to say whether El Nino conditions will take hold, farmers are struggling with very low soil moisture levels in many regions.

"A continuation of this dry weather would not be good news for next season's winter crop," Mr Collins said. "If it stays as dry and as hot as it has been recently, then there will be lower production [for the summer crop] than what we have forecast."

While there was a bumper winter crop, land planted for summer crops fell 15 per cent on a year earlier. Output is expected to drop by 25 per cent to about 4 million tonnes of crops ranging from wheat to sorghum and cotton, ABARES said.